Seat air conditioning unit

ABSTRACT

In an air conditioning unit for a seat, a duct forms a first outlet port through which air is blown to a seat surface and a second outlet port for discharging air. A heat exchanger unit having a thermoelectric effect element is disposed in the duct. An air volume control device is disposed in a duct to control a ratio of air introduced to the first outlet port to air introduced in an inlet port of the duct. In a draft mode, the air volume control device is operated such that the volume of air introduced to the first outlet port is larger than that in a normal mode. In a predetermined condition, the air volume control device is operated in the draft mode and an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate in the heat exchanger unit is smaller than that in the normal mode.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Applications No.2005-138609 filed on May 11, 2005, No. 2006-46506 filed on Feb. 23,2006, and No. 2006-46507 filed on Feb. 23, 2006, the disclosures ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a seat air conditioning unit that blowsair from a seat surface.

BACKGROUND OF THE INVENTION

According to a seat air conditioning unit disclosed in JapaneseUnexamined Patent Publication No. 10-44756, a temperature of air to beblown from a surface of a seat is increased or reduced through a heatexchanger unit having a Peltier element so as to improve a feeling of apassenger seating on the seat. A flow of air is produced by a blowerunit and is introduced to the heat exchanger unit. In the heat exchangerunit, a first heat exchanger is disposed on a heat absorbing side of thePeltier element and a second heat exchanger is disposed on a heatradiating side of the Peltier element. Air that has passed through thefirst heat exchanger is blown from the seat surface, and air that haspassed through the second heat exchanger is discharged to an outside ofthe seat.

In the seat air conditioning unit, when humidity between the passengerand the seat exceeds a predetermined level, an air mix door is opened sothat the air passing through the first heat exchanger and the airpassing through the second heat exchanger are mixed. The mixed air isblown from the seat surface. Accordingly, a moist feeling of thepassenger reduces.

Also, there is another seat air conditioning unit that blows air insideof a passenger compartment from a seat surface without controlling atemperature of the air through a heat exchanger unit. In general, whenthe seat surface is hot, e.g., in summer, it is required to cool theseat surface in a short time (a transitional quick cooling operation) soas to improve a seat feeling. On the contrary, when the seat surface isvery cold e.g., in winter, it is required to heat the seat surface in ashort time (a transitional quick heating operation) to improve the seatfeeling.

Regarding the former seat air conditioning unit, in the transitionalstate in which the quick cooling operation or the quick heatingoperation is required, the air that has passed through the first heatexchanger is blown from the seat surface. However, the air that haspassed through the second heat exchanger is discharged to the outside ofthe seat as a waste heat. Therefore, it is difficult to blow asufficient volume of air from the seat surface in the transitionalstate.

In the latter seat air conditioning unit, the air is not discharged asthe waste heat even in the transitional state. Therefore, a sufficientvolume of air is blown from the seat surface. However, the temperatureof the air to be blown from the seat surface is not controlled. That is,the air to be blown from the seat surface has a temperature equal to atemperature of the air inside the passenger compartment. Therefore, itis difficult to provide a sufficient cooling effect, particularly, in anormal operation.

SUMMARY OF THE INVENTION

The present invention is made in view of the foregoing matter, and it isan object of the present invention to provide a seat air conditioningunit having a draft effect by blowing the large volume of air in atransitional state and a cooling or heating effect in a normaloperation.

According to a first aspect of the present invention, an airconditioning unit for a seat has a duct, a heat exchanger unit, and anair volume control device. The duct defines a passage space, an inletport through which air is introduced in the passage space, and a firstoutlet port through which the air is blown from a seat surface. Thepassage space of the duct separates into a first passage communicatingwith the first outlet port and a second passage space defining a secondoutlet port for discharging air to an outside of the seat.

The heat exchanger unit has a thermoelectric effect element, a firstheat exchanger and a second heat exchanger. The thermoelectric effectelement has a first side and a second side. One of the first side andthe second side defines a heat absorbing side and the other one of thefirst side and the second side defines a heat radiating side. The heatradiating side and the heat radiating side are switched according to aflow direction of an electric current in the thermoelectric effectelement. The first heat exchanger is disposed adjacent to the first sidefor performing heat exchange with air flowing in the first passage. Thesecond heat exchanger is disposed adjacent to the second side forperforming heat exchange with air flowing in the second passage.

The air volume control device is disposed in the duct for changing aratio of air introduced to the first outlet port to the air introducedin the inlet port. In a normal mode, the thermoelectric effect elementis energized and the air volume control device is operated so that airpassing through the first heat exchanger is introduced to the firstoutlet port and air passing through the second heat exchanger isdischarged through the second outlet port. In a draft mode, the airvolume control device is operated so that the ratio of air introduced tothe first outlet port to the air introduced in the inlet port is largerthan that in the normal mode. In a predetermined condition, the airvolume control device is operated in the draft mode and an electriccurrent supply to the thermoelectric effect element is controlled suchthat a heat exchange rate in the first and second heat exchangers issmaller than that in the normal mode.

Accordingly, the ratio of air blown from the first outlet port to theair introduced in the inlet port is changed between the draft mode andthe normal mode. Namely, in the draft mode, the volume of air blown fromthe seat surface is larger than that in the normal mode. Therefore, adraft effect improves. On the other hand, in the normal mode, the airblown from the first outlet port has an air conditioning effect throughthe first heat exchanger. Further, in the predetermined condition, theheat exchange rate in the heat exchanger unit is smaller than that inthe normal mode, and the air volume control device is operated in thedraft mode. Accordingly, the large volume of air is blown from the seatsurface with reduced power consumption in the draft mode.

According to a second aspect of the present invention, the duct furtherdefines a bypass passage for allowing the air introduced in the inletport to bypass the first heat exchanger and the second heat exchanger.The bypass passage communicates with the first outlet port. The airvolume control device is disposed in the duct for controlling the volumeof air flowing in the bypass passage. In the normal mode, thethermoelectric effect element is energized. Also, the air passingthrough the first heat exchanger is introduced to the first outlet portand the air passing through the second heat exchanger is introduced toand discharged from the second outlet port. In the draft mode, the airvolume control device is operated to increase a volume of air flowingthrough the bypass passage so that the ratio of air introduced to thefirst outlet port to the air introduced in the inlet port is larger thanthat in the normal mode.

Accordingly, the ratio of air introduced to the first outlet port to theair introduced in the inlet port is changed between the draft mode andthe normal mode. Namely, in the draft mode, the volume of air blown fromthe seat surface is larger than that in the normal mode since the volumeof air passing through the bypass passage is increased by the operationof the air volume control device. Accordingly, a draft effect on theseat surface improves. On the other hand, in the normal mode, the airblown from the first outlet port has an air conditioning effect throughthe first heat exchanger. Further, since the air is introduced to thefirst outlet port through the bypass passage, a pressure loss reduces.With this, the volume of air blown from the first outlet port increases.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description made withreference to the accompanying drawings, in which like parts aredesignated by like reference numbers and in which:

FIG. 1 is a schematic diagram of a seat air conditioning unit accordingto a first example embodiment of the present invention;

FIG. 2 is a flow chart for showing a procedure of a control operation ofthe seat air conditioning unit according to the first exampleembodiment;

FIG. 3 is a chart for showing a timing of switching an operation modebetween a draft mode and a normal mode and an electric current supply toa Peltier element in the control operation according to the firstexample embodiment;

FIG. 4 is a graph for showing a change of a seat temperature with timein a cooling down operation according to the first example embodiment;

FIG. 5 is a chart for showing a timing of switching the operation modeand an electric conduction state of the Peltier element according to afirst modification of the first example embodiment shown in FIG. 3;

FIG. 6 is a flow chart for showing a procedure of the control operationaccording to the first modification shown in FIG. 5;

FIG. 7 is a chart for showing a timing of switching the operation modeand an electric conduction state of the Peltier element according to asecond modification of the first example embodiment shown in FIG. 3;

FIG. 8 is a flow chart for showing a procedure of the control operationaccording to the second modification shown in FIG. 7;

FIG. 9 is a flow chart for showing a procedure of the control operationaccording to a second example embodiment of the present invention;

FIG. 10 is a flow chart for showing a procedure of the control operationaccording to a modification of the second example embodiment;

FIG. 11 is a schematic diagram of a part of the seat air conditioningunit according to a third example embodiment of the present invention;

FIG. 12 is a schematic diagram of a part of the seat air conditioningunit according to a fourth example embodiment of the present invention;

FIG. 13 is a schematic diagram of a part of the seat air conditioningunit according to a fifth example embodiment of the present invention;

FIG. 14 is a schematic diagram of a past of the seat air conditioningunit according to a sixth example embodiment of the present invention;

FIG. 15 is a schematic diagram of a part of the seat air conditioningunit according to a modification of the fourth example embodiment;

FIG. 16 is a schematic diagram of a part of the seat air conditioningunit according to another modification of the fourth example embodiment;and

FIG. 17 is a schematic diagram of a par of the seat air conditioningunit according to further another modification of the fourth exampleembodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT

A first example embodiment of the present invention will now bedescribed with reference to FIGS. 1 to 4. As shown in FIG. 1, a seat airconditioning unit 1 of the first example embodiment is for examplemounted to a seat bottom 21 of a seat 20. Alternatively, the seat airconditioning unit 1 can be mounted to a seat back 22.

The seat air conditioning unit 1 has a duct 2, a blower 4 and a heatexchanger unit 9. The duct 2 forms an inlet port 3 at one end (left endin FIG. 1) and the blower unit 4 is located upstream of the inlet port3. The heat exchanger unit 9 is located downstream of the blower unit 4in the duct 2. The blower unit 4 sucks air and blows the air into theduct 2. The seat air conditioning unit 1 is for example used in avehicle. In this case, the blower unit 4 sucks air inside a passengercompartment. The blower unit 4 is disposed such that the air is fullyintroduced into a passage space of the duct 2 through the inlet port 3.In FIG. 1, an axial flow fan is illustrated as a fan of the blower unit4. Instead, the blower unit 4 can have a centrifugal fan.

The passage space of the duct 2 is divided into a first passage 5 and asecond passage 6 downstream of the inlet port 3. The duct 2 forms afirst outlet 13 at a downstream end of the first passage 5 and a secondoutlet 14 at a downstream end of the second passage 6.

The first outlet 13 communicates with seat openings 24, so that the airintroduced to the first outlet 13 is blown from a seat surface of theseat 20 through the seat openings 24. Here, the first passage 5, thefirst outlet 13 and the seat openings 24 form a channel through aconditioning air flows. The second outlet 14 serves as an opening fordischarging a waste heat. The air (waste heat air) passing through thesecond passage 6 is discharged to an outside of the seat 20 through thesecond outlet 14.

The heat exchanger unit 9 is located between the inlet port 3 and thefirst and second outlets 13, 14 in the duct 2. The heat exchanger unit 9includes a Peltier element 8, a first heat exchanger 10 and a secondheat exchanger 11. The Peltier element 8 is provided as a thermoelectriceffect element, and has a first side 8 a and a second side 8 b. In acooling operation, the first side 8 a functions as a heat absorbing sideand the second side 8 b functions as a heat radiating side. The heatabsorbing side and the heat radiating side of the Peltier element 8 areswitched according to a flow direction of electric current in thePeltier element 8.

The first heat exchanger 10 and the second heat exchanger 11 arearranged adjacent to the first side 8 a and the second side 8 b of thePeltier element 8, respectively, and use heat from the Peltier element8.

The Peltier element 8 generally has a plate shape and is disposed topartly form a separation wall 7 between the first passage 5 and thesecond passage 6. The first heat exchanger 10 is located in the firstpassage 5 and the second heat exchanger 11 is located in the secondpassage 6. Namely, the air passing through the first heat exchanger 10is fully introduced to the first outlet 13 through the first passage 5.Likewise, the air passing through the second heat exchanger 11 is fullyintroduced to the second outlet 14 through the second passage 6.

In the duct 2, a first door 12 is provided upstream of the second heatexchanger 11 as a first open and close member. The first door 12 isactuated by a door motor 31 through a link 32. The first door 12 issupported to move between a normal mode position (shown in dashed linein FIG. 1) and a draft mode position (shown in a solid line in FIG. 1).When the first door 12 is at the normal mode position, the first passage5 and the second passage 6 are fully open. When the first door 12 is atthe draft mode position, the second passage 6 is fully closed and thefirst passage 5 is open.

In the normal mode, that is, when the first door 12 is at the normalmode position, the air blown in the inlet port 3 is separated into thefirst passage 5 and the second passage 6. The air in the first passage 5is cooled through the first heat exchanger 10 and introduced to thefirst outlet 13. The air in the second passage 6 is heated through thesecond heat exchanger 11 and introduced to the second outlet 14. In theexample embodiment shown in FIG. 1, the second passage 6 is located onthe second side 8 b of the Peltier element 8. Thus, the heated air isdischarged from the second outlet (heat waste opening) 14 to the outsideof the seat 20.

In a draft mode, that is, when the first door 12 is at the draft modeposition, the air introduced in the inlet port 3 is fully introducedinto the first heat exchanger 10 and then introduced to the first outletport 13 through the first passage 5. At this time, the air is restrictedfrom passing through the second heat exchanger 11 by the first door 12.Accordingly, in the draft mode, the volume of air introduced in thefirst outlet 3 is substantially equal to the volume of air introduced tothe inlet port 3, i.e., the volume of air produced by the blower unit 4.Namely, the volume of air blown from the first outlet 13 in the draftmode is larger than that in the normal mode, with respect to the samevolume of air introduced in the inlet port 3.

Next, an electric control part of the seat air conditioning unit 1 willbe described. The seat air conditioning unit 1 has an ECU 30 as acontrol means. The ECU 30 is constructed of a microcomputer andperipheral circuits.

The ECU 30 is connected to an inside air temperature sensor 33 and aseat temperature sensor 34. The inside air temperature sensor 33 is forexample located adjacent to a suction side of the blower unit 4. Theinside air temperature sensor 33 detects a temperature of the inside airto be introduced into the suction port 3 and outputs a signal Tr of thedetected inside air temperature to the ECU 30.

The seat temperature sensor 34 detects a temperature of the seat 20 andoutputs a signal Ts of the detected seat temperature 20 to the ECU 30.The seat temperature sensor 34 is for example located in a cushionmember 34 of the seat 20 to avoid directly receiving an effect of theair blown from the seat openings 24 and an effect of the heat exchangingunit 9.

The ECU 30 controls the blower unit 4 in duty system to produce thenecessary volume of air. Also, the ECU 30 controls the door motor 31 sothat the first door 12 is operated to the draft mode position and thenormal mode position.

Further, the ECU 30 controls the electric current supply to the Peltierelement 8 in duty system so as to control the quantity of heat absorbedto and radiated from the Peltier element 8.

In a Peltier system of the first example embodiment, which isconstructed of the Peltier element 8, the heat exchanger unit 9, theduct 2 and the blower unit 4, a value ΔPt is 5° C. Here, the value ΔPtis a difference between a temperature of air at an inlet side of thePeltier element 8, which corresponds to the inside air temperature Tr,and a temperature of air at an outlet side of the first heat exchanger10 when the Peltier element 8 and the blower unit 4 are operated at amaximum level. Namely, the value ΔPt is a temperature difference createdby the first heat exchanger 10 with respect the inside air temperatureTr, for cooling the seat surface of the seat 20.

Next, operation of the seat air conditioning unit 1 will be described.FIG. 2 shows a procedure of a control operation executed by the ECU 30.The control operation is started when an electric power supply to theECU 30 is switched on. For example, the electric power supply to the ECU30 is switched at a timing when a power switch (not sown) of the seatair conditioning unit 1 is turned on. Alternatively, the electric powersupply to the ECU 30 is switched on according to a timing when a door ofa parked vehicle is unlocked. In the latter case, the seat airconditioning unit 1 starts the operation in the draft mode before thepassenger sits on the seat 20, so the temperature of the seat 20 iseffectively reduced.

First, as an initial setting, the blower unit 4 is set to a shutdowncondition and the Peltier element 8 is set to off. That is, the electriccurrent to the Peltier element 8 is set to zero. Next, at a step S100,it is determined whether the seat temperature Ts is equal to or higherthan a threshold value T1 (e.g., 30° C.). When it is determined that theseat temperature Ts is lower than the threshold value T1, the procedureproceeds to a step S160. At the step S160, a normal operation isperformed.

When it is determined that the seat temperature Ts is equal to or higherthan the threshold value T1 at the step S100, the blower unit 4 isoperated at a step S110. At this time, the blower motor 4 a is operatedat a maximum level (e.g., duty ratio=99%) so that the fan 4 blows themaximum volume of air.

Next, at a step S120, it is determined whether the temperaturedifference between the detected seat temperature Ts and the inside airtemperature Tr is equal to or greater than the value ΔPt (5° C.). In thedraft mode, a large volume of air is blown from the seat openings 24without operating the Peltier element 8. Namely, the cooling efficiencyof the seat 20 enhances by the larger volume of air in the draft mode,as compared to a mode in which a relatively small volume of air cooledby the Peltier element 8 is blown from the seat openings 24. Therefore,when the temperature difference is equal to or higher than the valueΔPt, the operation is performed in the draft mode.

In the draft mode of the first example embodiment, the first door 12 isoperated to the draft mode position in the condition that the Peltierelement 8 is not energized and the blower unit 4 is operated at themaximum level (duty ratio=99%). Thus, the second passage 6 is closed.Namely, the inlet of the second heat exchanger 11 is closed, so thevolume of air introduced to the second passage 6 is zero. Accordingly,the volume of air discharged from the second outlet port 14 is zero.

In the draft mode, the electric current is not supplied to the Peltierelement 8. Therefore, even if the volume of air on the heat radiatingside, i.e., the volume of air flowing in the second heat exchanger 11 iszero, it is less likely that the Peltier element 8 will be broken.Further, a power consumption reduces.

According to the operation in the draft mode, the air introduced to theinlet port 3 from the blower unit 4 almost passes through the first heatexchanger 10 and the first passage 5 and then introduced to the seatopenings 24 through the first outlet 13, although there is a slightpressure loss. Accordingly, the ratio of air introduced to the firstport 13 to the of air introduced in the inlet port 3 is a maximum. Thatis, the volume of the air blown from the outlet port 13 is at themaximum level, with respect to the maximum volume of air introduced inthe inlet port 3.

Accordingly, in the draft mode, the air having the inside airtemperature Tr is blown from the seat openings 24 at the maximum level.This operation is effective to immediately cool down the heated seat 20.For example, in a bright ambience in summer, the seat temperature Ts(e.g., approximately 60° C.) is immediately reduced at least to a firstpredetermined level P1 (Tr+ΔPt, e.g., 45 to 50° C.).

This draft mode operation is performed until the temperature differencebetween the seat temperature Ts and the inside air temperature Trbecomes smaller than the value ΔPt. Namely, at the step S120, when thedifference between the seat temperature Ts and the inside airtemperature Tr is smaller than the value ΔPt, the procedure proceeds toa step S140 to shift the operation from the draft mode to the normalmode.

In the normal mode, first, the first door 12 is operated to the normalmode position from the draft mode position to open the second passage 6,i.e., the inlet of the second heat exchanger 11. Thus, the volume of airintroduced into the second passage 6 increases from zero to apredetermined level.

In this case, both of the first passage 5 and the second passage 6 areopen. Thus, the air introduced in the inlet port 3 is separated into thefirst passage 5 and the second passage 6.

Then, at a step S150, the Peltier element 8 is energized to perform aduty system control of the normal operation. Then, the procedureproceeds to the step S160 to perform the normal operation.

In the normal operation at the step S160, the normal cooling downoperation is performed in conditions similar to control conditions of ageneral seat air conditioning control using the Peltier element. Forexample, when the seat temperature Ts is equal to or higher than acomfortable temperature (e.g., 35° C.), the Peltier element 8 and theblower unit 4 are operated at maximum levels (duty ratio=99%).

When the seat temperature Ts reduces below the comfortable temperature(35° C.) as a result of the normal cooling down operation, a regularoperation is performed to maintain the seat temperature at thecomfortable temperature. In the regular operation, the Peltier element 8and the blower unit 4 are operated at a half capacity (duty ratio=50%).

FIG. 3 shows a mode switching and an electric current supply to thePeltier element 8 with respect to the seat temperature Ts in the abovecontrol operation. As shown in FIG. 3, when the seat temperature Ts isequal to or higher than the threshold value T1, the draft mode isselected and the electric power is not supplied to the Peltier element8. Then, the seat temperature Ts reduces below the first predeterminedtemperature P1 (Tr+ΔPt), the operation mode is switched to the normalmode and the electric current is supplied to the Peltier element 8.

Next, advantageous effect of the above control operation will bedescribed with reference to FIG. 4. FIG. 4 shows the change of the seattemperature Ts in the cooling down operation with respect to an elapsedtime.

At an initial point, i.e., when the elapsed time is zero, a temperatureof outside air is 40° C. under bright sunlight. Also, the inside airtemperature Tr is approximately 45° C., and the seat temperature Ts is60° C. A dotted line A shows a change of the seat temperature Ts whenthe control operation is performed only in the draft mode (large volumeof air, Pelier element off). A dashed line B shows the change of theseat temperature Ts when the control operation is performed only in thenormal mode (Peltier element on, the second passage 6 open). A solidline C shows the change of the seat temperature Ts when the controloperation is performed in the manner of the first example embodimentdescribed above.

Here, a vehicle air conditioner starts its operation from the initialpoint. Thus, the inside air temperature Tr reduces to 40° C. severalminutes (e.g., about 5 minutes) after an operation of the vehicle airconditioner is started. The inside air temperature Tr becomes a settingtemperature (25° C., which is set by the vehicle air conditioner, in aregular state.

In the operation condition A, the inside air having the temperature Tr,which is 15 to 20° C. lower than the seat temperature Ts, is blown at aninitial stage. Also, the large volume of air is blown. Thus, theoperation condition A provides a cooling effect higher than that of theoperation condition B. The passenger on the seat 20 is likely to feelairflow and cool.

As the time elapses, the seat temperature Ts reduces. When the seattemperature Ts approaches the inside temperature Tr, it is difficult toabsorb heat of the seat 20 in the operation condition A. Thus, the seattemperature Ts reaches a level of saturation due to a body temperatureof the passenger in the regular state.

In the operation condition B, even when the seat temperature Tsapproaches the inside temperature Tr with the elapse of time, a highcooling effect is provided. Further, it is possible to cool the seat 20to a temperature (e.g., equal to or lower than 35° C. in summer) thatthe passenger feels cold. Thus, the seat temperature Ts is effectivelycontrolled by using the Peltier element 8.

Here, in the operation condition B, the electric power is continuouslysupplied to the Peltier element 8 without performing a temperaturecontrol. Thus, the line B shows a seat cooling capacity when theelectric power is continuously supplied to the Peltier element 8.

As shown in the operation condition C, at an initial stage of thecooling down operation right after the operation of the seat airconditioning unit 1 is started, the seat temperature Ts is immediatelyreduced by the large volume of air in the draft mode. Then, when theseat temperature Ts approaches the inside temperature Tr, the operationmode is switched to the normal mode. Thus, the seat temperature Ts ispositively controlled by using the Peltier element 8 in the normal mode.Accordingly, this control operation is effective to provide a coolfeeling to the passenger.

The first example embodiment will be modified as follows. FIG. 5 shows afirst modification of the first example embodiment. As shown in FIG. 5,when the seat temperature Ts is equal to or higher than a firstpredetermined temperature P1, the operation is performed in the draftmode in a condition that the Peltier element 8 is energized. In thefirst modification, the first predetermined temperature P1 is Tr+ΔPt+1°C. When the seat temperature Ts reduces below the first predeterminedtemperature P1 (Tr+ΔPt+1° C.), the Peltier element 8 is energized. Then,the seat temperature Ts reduces below a second predetermined temperatureP2 (Tr+ΔPt), the operation mode is switched to the normal mode.

There is a time delay to reduce the temperature of the Peltier element 8so as to have sufficient cooling effect after the electric currentsupply to the Peltier element 8 is started. Therefore, in the firstmodification, the Peltier element 8 is energized before the operationmode is switched from the draft mode to the normal mode. The temperatureof air is immediately reduced at the same time as reducing the volume ofair. Therefore, even if the volume of air is reduced, the passenger whohas been satisfied with the draft feeling can feel cool at that timing.

The procedure of the control operation of the first modification will bedescribed with reference to FIG. 6. Similar to the procedure shown inFIG. 2, when the seat temperature Ts is equal to or higher than thethreshold value T1, the blower unit 4 is operated at the maximum levelat the step S110.

Next, at a step S120 a, it is determined whether the seat temperature Tsis lower than the first predetermined temperature P1 (Tr+ΔPt+1° C.).When the seat temperature Ts is equal to or higher than the firstpredetermined temperature P1, the operation is performed in the draftmode at the step S130.

Then, when the seat temperature Ts reduces below the first predeterminedtemperature P1, it is determined whether the seat temperature Ts islower than the second predetermined temperature P2 (Tr+ΔPt) at a stepS120 b. When the seat temperature Ts is equal to or higher than thesecond predetermined temperature P2, the Peltier element 8 is energizedat the step S150. Then, when the seat temperature Ts reduces lower thanthe second predetermined temperature P2, the operation mode is switchedto the normal mode at a step S140. Then, the normal operation isperformed at the step S160.

In the first modification of the first example embodiment, thedifference between the first predetermined temperature P1 and the secondpredetermined temperature P2 is 1° C. This temperature difference can bemodified to another fixed value or a variable value calculated based onthe inside temperature Tr.

FIG. 7 shows a second modification of the first example embodiment. Asshown in FIG. 7, when the seat temperature Ts is equal to or higher thana first predetermined temperature P1 (Tr+ΔPt), the operation isperformed in the draft mode and the Peltier element 8 is not energized.When the seat temperature Ts reduces below the first predeterminedtemperature P1, the Peltier element 8 is energized. Then, when apredetermined time Et1 (e.g., 10 seconds) has elapsed since the Peltierelement 8 was energized, the operation mode is switched to the normalmode. For example, the predetermined time Et1 is set by using a timer.

Also in the second modification, the Peltier element 8 is energizedbefore the operation mode is switched from the draft mode to the normalmode. Accordingly, advantageous effects similar to those of the firstmodification are provided.

The control operation of the second modification will be described withreference to FIG. 8. The control operation shown in FIG. 8 is differentfrom the control operation shown in FIG. 6 at steps S120 c and S120 d.The first predetermined temperature P1, which is the threshold value atthe step S120 c, is Tr+ΔPt. At the S120 d, it is determined whether thepredetermined time period Et1 has elapsed. Steps other than the stepsS120 c and S120 d are similar to those of the first modification shownin FIG. 6.

In the control operations shown in FIGS. 2, 6, 8, the threshold valuecompared to the seat temperature Ts is set by using the insidetemperature Tr and ΔPt. However, the threshold value can be changedbased on a type of vehicle, a region in use, a user, or a use condition.Further, the threshold value can be a fixed value.

Next, a second example embodiment of the present invention will bedescribed with reference to FIG. 9. In the second example embodiment,structure of the seat air conditioning unit 1 is similar to that of thefirst example embodiment. Thus, description of like structures will notbe repeated. However, the control operation performed by the ECU 30 isdifferent from that of the first example embodiment. Hereafter, thecontrol operation of the second example embodiment will be described.

When the electric power supply to the ECU 30 is switched on, the initialsetting is performed in a manner similar to the first exampleembodiment. Next, at a step S105, it is determined whether the insidetemperature Tr detected by the inside air temperature sensor 33 is equalto or higher than a threshold value T2 (e.g., 30° C.). The thresholdvalue T2 is can be changed based on a type of vehicle, a region in use,a user, or a use condition.

When the inside temperature Tr is lower than the threshold value T2, theprocedure proceeds to step S160, so the normal operation is performed,similar to the first example embodiment.

When the inside temperature Tr is equal to or higher than the thresholdvalue T2 at the step S105, the blower unit 4 is operated at the maximumlevel (duty ratio=99%) at the step S110, similar to the first exampleembodiment. Next, at a step S115, it is determined whether apredetermined time period Et2 (e.g., 2 minutes) has elapsed. Thepredetermined time period Et2 is previously set by the timer. Thepredetermined time period Et2 is changed based on various conditionssuch as an assumed use condition or a type of vehicle.

When it is determined that the predetermined time period Et2 has notelapsed at the step S115, the operation is performed in the draft modeat the step S130. In the draft mode, the Peltier element 8 is notenergized, and the blower unit 4 is operated at the maximum level (dutyratio=99%), similar to the draft mode of the first example embodiment.In this condition, the first door 12 is operated to the draft modeposition to close the inlet of the second heat exchanger 11. Thus, thevolume of air discharged from the second outlet port 14 is zero.

According to the operation in the draft mode, since the second passage 6is closed with the first door 12 in a condition that the electriccurrent is not supplied to the Peltier element 8, the air introduced inthe inlet port 3 almost introduced to the first outlet port 13 and blownfrom the seat openings 24. Thus, the large volume of air is blown fromthe seat openings 24. Accordingly, the seat temperature Ts isimmediately reduced close to the inside air temperature Tr by the drafteffect.

When the predetermined time Et2 has elapsed since the operation in thedraft mode was started, that is, it is determined YES at the step S115,the operation mode is switched to the normal mode at the step S140.First, the first door 12 is operated to the normal mode position atwhich the second passage 6 is opened, i.e., the inlet of the second heatexchanger 11 is open. Thus, the volume of air introduced into the secondpassage 6 increases to the predetermined level from zero.

In this case, the first passage 5 and the second passage 6 are open.Thus, the air introduced in the inlet port 3 separates into the firstpassage 5 and the second passage 6. Then, similar to the first exampleembodiment, at the step S150, the Peltier element 8 is energized toperform the normal operation in duty system control. Then, the normaloperation is performed at the step S160.

In the normal operation in the step S160, the normal cooling downoperation is performed in conditions similar to control conditions ofthe general seat air conditioning control using the Peltier element. Forexample, when the seat temperature Ts is equal to or higher than thecomfortable temperature (e.g., 35° C.), the Peltier element 8 and theblower unit 4 are operated at the maximum level (duty ratio=99%).

When the seat temperature Ts reduces below the comfortable temperature(35° C.) as a result of the normal cooling down operation, the regularoperation is performed to maintain the seat temperature at thecomfortable temperature. In the regular operation, the Peltier element 8and the blower unit 4 are operated at a half capacity (duty ratio=50%).

Accordingly, the control operation of the second example embodimentprovides advantageous effects similar to those of the first exampleembodiment.

In the second example embodiment shown in FIG. 9, the timing ofswitching the operation mode from the draft mode to the normal mode isdetermined based on the elapsed time Et2 at the step S115. However, thecontrol operation of the second example embodiment will be modified asshown in FIG. 10. In FIG. 10, a step S125 for determining whether theinside temperature Tr is equal to or lower than a predeterminedtemperature T3 that is lower than the threshold value T2 is provided inplace of the step S115 of FIG. 9. Accordingly, when the insidetemperature Tr is equal to or lower than the predetermined temperatureT3 that is lower than the threshold value T2, the draft mode operationis terminated and switched to the normal mode.

A third example embodiment will be described with reference to FIG. 11.As shown in FIG. 11, a second door 15 is provided as the first open andclose member, in place of the first door 12 of the first and secondexample embodiments. Structures other than the second door 15 aresimilar to those of the first and second example embodiments. In FIG.11, only the part from the inlet port 3 to the first and second outletports 13, 14 is illustrated. Further, like components are denoted bylike reference characters and a description thereof is not repeated.

The second door 15 is located downstream of the heat exchanger unit 9.Further, the second door 15 is supported to open and close the secondpassage 6 at a position downstream of the second heat exchanger 11. Whenthe second door 15 is at a position to close the second passage 6, anopening 15 a formed on the separation wall 7 between the first passage 6and the second passage 7 is open. Thus, the air passing through thesecond heat exchanger 11 flows into the first passage 5 through theopening 15 a. When the second door 15 is at a position to close theopening 15 a, the second passage 6 is fully open. Thus, the air passingthrough the second heat exchanger 11 is restricted from flowing into thefirst passage 5. The second door 15 is rotated by the door motor 31through a link 32 a, similar to the first door 12 of the first andsecond example embodiments.

In the third example embodiment, the ECU 30 performs the controloperation in a manner similar to the first and second exampleembodiments shown in FIGS. 2, 6, 8, 9 and 10, except the operation ofthe second door 15. The second door 15 is operated in the followingmanner.

In the normal mode in which the Peltier element 8 is energized to havethe cooling effect by the first heat exchanger 10 to have coolingeffect, the second door 15 is operated to a normal mode position shownby dotted line in FIG. 11. Namely, the opening 15 a is fully closed andthe second passage 6 is open so that the air that receives heat from thePeltier element 8 through the second heat exchanger 11 is dischargedfrom the second outlet port 14 as the waste heat.

Since the second door 15 is positioned to close the opening 15 a andopen the second passage 6 in the normal mode, the air is distributed inthe manner similar to that in the normal mode of the first and secondexample embodiments.

In the draft mode, that is, at the step S130 of FIGS. 2, 6, 8, 9, and10, the second door 15 is operated to a draft mode position shown by asolid line in FIG. 11. Namely, the second door 15 fully closes thesecond passage 6 and opens the opening 15 a. After the termination ofthe draft mode, that is, at the step S140 of FIGS. 2, 6, 8, 9 and 10,the second door 15 is operated to the normal mode position shown by thedotted line in FIG. 11.

Accordingly, in the draft mode, the air passing through the second heatexchanger 11 flows into the first passage 5 through the opening 15 a.Since both the air passing through the first heat exchanger 10 and theair passing through the second heat exchanger 11 are introduced to thefirst outlet port 13, the ratio of the air introduced to the firstoutlet port 13 to the air introduced to the inlet port 3 increases.

In the draft mode, the Peltier element 8 is not energized. Therefore,the air passing through the second heat exchanger 11 does not receiveheat from the Peltier element 8 and has the temperature similar to thetemperature of the inside air.

Also in the third example embodiment, advantageous effects similar tothose of the first and second example embodiments are provided.

Next, a fourth example embodiment will be described with reference toFIG. 12. As shown in FIG. 12, the duct 2 has a bypass passage 16 and athird door 17 as a second open and close member, in place of the firstdoor 12 of the first open and close member. Other structures are similarto those of the first and second example embodiments. In FIG. 12, onlythe part from the inlet port 3 to the first and second outlet ports 13,14 is illustrated. Further, like components are denoted by likereference characters and a description thereof is not repeated.

The bypass passage 16 is disposed to allow the air to bypass the firstheat exchanger 10. For example, the bypass passage 16 is located on theopposite side as the second heat exchanger 11, with respect to the firstheat exchanger 10, in the first passage 5. The third door 17 is locatedadjacent to an inlet of the bypass passage 16 to open and close thebypass passage 16. The third door 17 is operated by the door motor 31through a link 32 b, similar to the first door 12 of the first andsecond example embodiments.

In the fourth example embodiment, the ECU 30 performs the controloperation, in a manner similar to the first and second exampleembodiment, except the operation of the third door 17. The third door 17is operated in the following manner, in place of the first door 12.

First, in the normal mode in which the Peltier element 8 is energized tohave the cooling effect by the first heat exchanger 10, the third door17 is operated to a normal mode position shown by dotted line in FIG.12. Namely, the third door closes the bypass passage 16. Thus,approximately half of the air introduced in the inlet port 3 is cooledthrough the first heat exchanger 10. The cooled air passes through thefirst outlet port 13 and is blown from the seat openings 24.

The remaining half of the air is heated through the second heatexchanger 11 according to the operation of the Peltier element 8. Theheated air is discharged from the second outlet port 14 to the outsideof the seat 20. Since the third door 17 closes the bypass passage 16 inthe normal mode, the air is distributed in a manner similar to that inthe normal mode of the first to third example embodiments.

In the draft mode, that is, at the step S130 of FIGS. 2, 6, 8, 9, and10, the third door 17 is operated to a draft mode position shown bysolid line in FIG. 12. Namely, the third door 17 is positioned to fullyopen the bypass passage 16. After the termination of the draft mode,that is, at the Step S140 of FIGS. 2, 6, 8, 9, and 10, the third door 17is operated to the normal mode position shown by the dotted line in FIG.12.

Accordingly, the pressure loss in the first passage 5 reduces in thedraft mode. Therefore, the volume of air introduced to the first outletport 13 through the first passage 5 increases. Namely, the ratio of theair blown from the first outlet port 13 to the air introduced in theinlet port 3 increases, as compared to a case without having the bypasspassage 16.

Also in the fourth example embodiment, advantageous effects similar tothose of the first and second example embodiments are provided.

Similar to the above example embodiments, the Peltier element 8 is notenergized in the draft mode. Therefore, power consumption reduces.However, since the inlet of the second heat exchanger 11 is always openand the air passing through the second heat exchanger 11 is alwaysdischarged from the second outlet port 14 to the outside of the seat 20,it is not always necessary to stop the electric current supply to thePeltier element 8.

Therefore, in the draft mode of the steps S110 in FIGS. 2, 6, 8, 9, and10, the electric current can be supplied to the Peltier element 8. Thus,the air can be cooled through the first heat exchanger 10 and the cooledis blown from the first outlet port 13 in the draft mode.

In this case, the cooling effect in the draft mode is lower than that inthe normal mode, because the volume of air in the bypass passage 16increases. However, since the volume of air blown from the seat openings24 increases, the draft effect improves. Thus, the seat temperature Tsis further reduced by the cooled air having the temperature lower thanthe inside temperature Tr.

Further, the volume of the air blown from the first outlet 13 isincreased since the pressure loss in the first passage 5 is reduced.Therefore, a power required to the blower unit 4 reduces. Furthermore,noise effect reduces.

Next, a fifth example embodiment will be described with reference toFIG. 13. As shown in FIG. 13, the duct 2 has the second door 15 as thefirst open and close member, which is similar to the second door 15 ofthe third example embodiment, in place of the first door 12. Also, theduct 2 has the third door 17 as the second open and close member, whichis similar to the third door 17 of the fourth example embodiment.Further, the duct 2 has the bypass passage 16. Other structures aresimilar to the first and second example embodiments. In FIG. 13, onlythe part from the inlet port 3 to the first and second outlet ports 13,14 is illustrated. Further, like components are denoted by likereference characters and a description thereof is not repeated.

Similar to the third example embodiment, the second door 15 as the firstopen and close member is located downstream of the second heat exchanger11 in the second passage 6. The second door 15 is operated to open andclose the second passage 6 and the opening 15 a formed in the separationwall 7. Similar to the fourth example embodiment, the bypass passage 16is formed in the first passage 5 to allow the air to bypass the firstheat exchanger 10. Also, the third door 17 as the second open and closemember is located at the inlet of the bypass passage 16 to open andclose the bypass passage 16. The second door 15 and the third door 17are simultaneously operated by the door motor 31 through the links 32 a,32 b.

Also in the fifth example embodiment, the ECU 30 performs the controloperation in a manner similar to that of the first and second exampleembodiments, except the operation of the second door 15 and the thirddoor 17. The second door 15 and the third door 17 are operated in thefollowing manner.

First, in the normal mode in which the Peltier element 8 is energized tohave the cooling effect by the first heat exchanger 10, the second door15 is at the normal mode position shown by dotted line in FIG. 13. Also,the third door 17 is at a position shown by dotted line in FIG. 13.Namely, the second door 15 fully closes the opening 15 a and fully opensthe second passage 6 so that the air passing through the second heatexchanger 11 is discharged from the second outlet port 14 to the outsideof the seat 20. The third door 17 closes the bypass passage 16. Thus,approximately half of the air introduced in the inlet port 3 isintroduced to the first heat exchanger 10 and cooled. The cooled air isblown from the seat openings 24 through the first outlet port 13.

In the draft mode, that is, at the step S130 of FIGS. 2, 6, 8, 9, and10, the second door 15 is operated to the position shown by solid linein FIG. 13. Also, the third door 17 is operated to the position shown bysolid line in FIG. 13. Namely, the second door 15 fully closes thesecond passage 6 and fully opens the opening 15 a. The third door 17fully opens the bypass passage 16.

After the termination of the draft mode, that is, at the step S140 ofFIGS. 2, 6, 8, 9, and 10, the second door 15 is operated to the positionshown by solid line in FIG. 13. Also, the third door 17 is operated tothe position shown by dotted line in FIG. 13.

Accordingly, in the draft mode, the air passing through the firstpassage 5 and the air passing through the second heat exchanger 11 areintroduced to the first outlet port 13. Therefore, the ratio of the airintroduced to the first outlet port 13 to the air introduced in theinlet port 3 increases, as compared to that in the normal mode.

Further, the pressure loss in the first passage 5 reduces since thebypass passage 16 is open in the draft mode. Therefore, the volume ofair passing through the first passage 5 increases. Furthermore, sincethe air passing through the second heat exchanger 11 is introduced tothe first passage 5 through the opening 15 a, the volume of air blownfrom the first outlet port 13 is increased larger than that of the firstto fourth example embodiments. In the draft mode, since the Peltierelement 8 is not energized, the air passing through the second heatexchanger 11 does not receive heat from the Peltier element 8 and hasthe temperature similar to that of the inside air.

Also in the fifth example embodiment, advantageous effects similar tothose of the first and second embodiments are provided.

The above example embodiments will be further modified in the followingmanner.

In the above example embodiments shown in FIGS. 11 and 12, the heatexchanger unit 9 are configured such that the air flows parallel to thePeltier element 8. Alternatively, a wall 10 a of the first heatexchanger 10, which faces the bypass passage 16, can be formed withopenings, as shown in FIG. 14.

For example, in the Peltier module including the Peltier element 8 andthe first and second heat exchangers 10, 11, fins 10 b, 11 b aregenerally provided along the surfaces 8 a, 8 b of the Peltier element 8for performing heat exchange. The fins 10 b, 11 b are sandwiched bywalls 10 a, 11. Here, the openings 10 c are formed on the wall 10 a.Instead of forming the openings 10 c on the wall 10 a, the wall 10 a canbe removed.

Accordingly, the air passing through the first heat exchanger 10 canflow upwardly toward the bypass passage 16. Therefore, the pressure lossof the air passing through the first heat exchanger 10 further reduces.In the example embodiment shown in FIG. 14, the openings 10 c areexemplary employed in the structure shown in FIG. 12. The openings 10 ccan be employed in the structure shown in FIG. 13.

As a modification of the fourth example embodiment shown in FIG. 12, thefirst door 12 as the first open and close member can be arrangedupstream of the second heat exchanger 11, as shown in FIG. 15. The firstdoor 12 is operated by the door motor 31 through the link 32, similar tothe first and second example embodiments. In this case, the ECU 30performs the control operation in a manner similar to the first andsecond example embodiments. Here, the first door 12 is operated in themanner similar to those of the first and second example embodiments. Thethird door 17 is operated in the manner similar to that of the fourthexample embodiment. In this case, the Peltier element 8 is not energizedin the draft mode.

In the example embodiment shown in FIG. 12, the third door 17 isarranged at the upstream position of the bypass passage 16.Alternatively, the third door 17 can be arranged at a positiondownstream of the first heat exchanger 10, as shown in FIG. 16.Alternatively, the third door 17 can be arranged at a substantiallymidstream position of the bypass passage 16, as shown in FIG. 17. Alsoin the example embodiments shown in FIGS. 13 and 15, the position of thethird door 17 can be arranged as shown in FIGS. 16 and 17.

Further, the bypass passage 16 can be formed in a differentconfiguration as long as it allows the air to bypass the first heatexchanger 10. For example, the bypass passage 16 can be formed on a sideof the second passage 6 so that the air bypasses the second heatexchanger 11. In this case, the air is introduced to the first outletport 13 from the bypass passage through a duct.

In the above example embodiments, the Peltier element 8 is notenergized, that is, the electric current to the Peltier element 8 iszero in the draft mode. Instead, the Peltier element 8 can be operatedat a small duty ratio in the draft mode as long as the rate of heatexchange in the first and second heat exchangers 10, 11 in the draftmode is smaller than that in the normal mode.

In the first example embodiment, the seat temperature Ts detected by theseat temperature sensor 34 is used as a physical value relating to thetemperature of the seat surface. In the second example embodiment, theinside temperature Tr detected by the inside air temperature sensor 33is used as the physical value relating to the temperature of the seatsurface. However, the temperature of the seat surface can be obtained ina different way.

For example, the temperature of the seat surface can be estimated bycorrecting the inside temperature Tr with one of the quantity of solarradiation, the outside temperature, a temperature of heat exchange thatis detected by a sensor provided downstream of the heat exchanger unit9. Alternatively, the temperature of the seat surface can be estimatedbased on the outside temperature, the quantity of solar radiation, and acumulative time thereof. Further, the temperature of the seat surfacecan be estimated based on the quantity of solar radiation, the outsidetemperature, and the temperature of heat exchange.

In the above example embodiments, the first, second and third doors 12,15, 17 are operated by the door motor 31 through the links 32, 32 a, 32b. However, the structure of the doors 12, 15, 17 are not limited to theillustrated example embodiments. For example, the second door 15 of thethird and fifth example embodiments can be formed of a material that isdeformable according to an ambient temperature, e.g., bimetal or shapememory alloy.

In such a case, when the temperature of air passing through the firstheat exchanger 10 reduces in a condition that the Peltier element 8 isenergized, the second door 15 opens the second passage 6 so that the airis discharged. When the ambient temperature is relatively high in acondition that the Peltier element 8 is not energized, the second door15 closes the second passage 6. Therefore, power used to operate thesecond door 15 reduces.

In the above example embodiments, it is mainly described about thecooling down operation for immediately cooling the temperature of theseat surface, for example when the seat temperature Ts is very high insummer. The above described example embodiments can be used to performwarming up operation for heating the seat surface. In this case, theelectric current is supplied to the Peltier element 8 in an oppositedirection. Thus, the heat absorbing side and the heat radiating side ofthe heat exchanger unit 9 are reversed.

For example, when the temperature of the seat surface is low in winter,the first door 12 in FIG. 1 is operated to close the inlet of the secondheat exchanger 11 so that the volume of air blown from the first outletport 13 increases. In this case, the Peltier element 8 is not energized.Thus, the air blown from the first outlet port 13 by the operation ofthe blower unit 4 has a temperature higher than the temperature of thecold seat surface. Accordingly, the seat surface is warmed.

Further, when the temperature of the seat surface approaches the insidetemperature, the operation mode is switched from the draft mode to thenormal mode. The electric current is supplied to the Peltire element 8so that the Peltier element 8 has the heat radiating surface on the sideof the first heat exchanger 10 and the heat absorbing surface on theside of the second heat exchanger 11. Also, the first door 12 isoperated to open the inlet of the second heat exchanger 11. Thus, theair heated through the first heat exchanger 10 is introduced to thefirst outlet port 13 through the first passage 5 and is blown from theseat openings 24. The air cooled through the second heat exchanger 11 isintroduced to the second outlet port 14 through the second passage 6 andis discharged to the outside of the seat 20.

In the above example embodiments, the blower unit 4 is operated at themaximum level in the draft mode. Here, the maximum level is determinedwithin a maximum level in an actual use condition satisfying the qualityin view of the performance and reducing vibration and noise.

The example embodiments of the present invention are described above.However, the present invention is not limited to the above exampleembodiments, but may be implemented in other ways without departing fromthe spirit of the invention.

1. An air conditioning unit for a seat for blowing air from a seatsurface, comprising: a duct defining an inlet port and a passage spacethrough which air introduced in the inlet port flows, the passage spaceseparating into a first passage and a second passage, the first passagedefining a first outlet port through which air is blown to the seatsurface, and the second passage defining a second outlet port throughwhich air is discharged; a heat exchanger unit disposed between theinlet port and the first and second outlet ports in the duct, the heatexchanger unit having a thermoelectric effect element, a first heatexchanger, and a second heat exchanger, the thermoelectric effectelement including a first side and a second side, one of the first sideand the second side radiating heat and the other one of the first sideand the second side absorbing heat according to a flow direction of anelectric current therein, the first heat exchanger disposed adjacent tothe first side for performing heat exchange with air flowing in thefirst passage, and a second heat exchanger disposed adjacent to thesecond side for performing heat exchange with air flowing in the secondpassage; and an air volume control device disposed in the duct forchanging a ratio of air introduced to the first outlet port to the airintroduced in the inlet port between a normal mode and a draft mode,wherein in the normal mode the thermoelectric effect element isenergized and the air volume control device is operated such that airpassing through the first heat exchanger is introduced to the firstoutlet port and air passing through the second heat exchanger isintroduced to and discharged from the second outlet port, and in thedraft mode the air volume control device is operated so that the ratioof air introduced to the first outlet port to the air introduced in theinlet port is larger than that in the normal mode, wherein in apredetermined condition, the air volume control device is operated inthe draft mode and an electric current supply to the thermoelectriceffect element is controlled such that a heat exchange rate in the firstand second heat exchangers is smaller than that in the normal mode. 2.The air conditioning unit according to claim 1, further comprising: ablower unit disposed upstream of the inlet port of the duct forproducing a flow of air into the inlet port.
 3. The air conditioningunit according to claim 2, wherein in the draft mode, the blower unit isoperated at a maximum level.
 4. The air conditioning unit according toclaim 1, wherein the predetermined condition is satisfied when aphysical value relating to a temperature of the seat surface is equal toor higher than a first predetermined value.
 5. The air conditioning unitaccording to claim 4, wherein when the physical value is lower than thefirst predetermined value, the thermoelectric effect element isenergized in a condition same as the normal mode, and when the physicalvalue is lower than a second predetermined value that is lower than thefirst predetermined value, the air volume control device is operated inthe normal mode.
 6. The air conditioning unit according to claim 4,wherein when the physical value is lower than the first predeterminedvalue, the thermoelectric effect element is energized in a conditionsame as the normal mode, and when a first predetermined time period haselapsed since the thermoelectric effect element was energized in thecondition same as the normal mode, the air volume control device isoperated in the normal mode.
 7. The air conditioning unit according toclaim 4, wherein when the physical value is lower than the firstpredetermined value, the air volume control device is operated in thenormal mode, and the thermoelectric effect element is energized in acondition same as the normal mode.
 8. The air conditioning unitaccording to claim 4, wherein when the physical value reduces below athird predetermined value that is lower than the first predeterminedvalue in a condition that the air volume control device is operated inthe draft mode and the electric current supply to the thermoelectriceffect element is controlled such that the heat exchange rate is smallerthan that of the normal mode, the air volume control device is operatedin the normal mode and the thermoelectric effect element is energized ina condition same as the normal mode.
 9. The air conditioning unitaccording to claim 4, wherein when a second predetermined time periodhas elapsed since the air volume control device was operated in thedraft mode and the electric current supply to the thermoelectric effectelement was controlled such that the heat exchange rate is smaller thanthat of the normal mode in a condition that the physical value is equalto or higher than the first predetermined value, the air volume controldevice is operated to the normal mode and the thermoelectric effectelement is energized in a condition same as that in the normal mode. 10.The air conditioning unit according to claim 1, wherein the air volumecontrol device includes a first open and close member, the first openand close member is disposed at a position upstream of the second heatexchanger to open and close the second passage to thereby control avolume of air introduced to the second outlet port, and in the draftmode the first open and close member is operated to fully close thesecond passage to restrict the air from flowing to the second outletport, to thereby increase a volume of air introduced to the first outletport.
 11. The air conditioning unit according to claim 1, wherein theair volume control device includes a first open and close member, thefirst open and close member is disposed to open and close the secondpassage at a position downstream of the second heat exchanger, when thefirst open and close member fully closes the second passage the airpassing through the second heat exchanger is allowed to flow in thefirst passage, and when the first open and close member opens the secondpassage the air passing through the second heat exchanger is restrictedfrom flowing in the first passage, and in the draft mode the first openand close member is disposed to fully close the second passage toincrease a volume of air introduced to the first outlet port.
 12. Theair conditioning unit according to claim 11, wherein the first open andclose member is formed of a material that deforms according to anambient temperature and the second passage is open and closed accordingto deformation of the first open and close member.
 13. The airconditioning unit according to claim 1, wherein the duct further definesa bypass passage through which air flows toward the first outlet portwhile bypassing the first heat exchanger and the second heat exchanger,the air volume control device includes a second open and close memberdisposed to open and close the bypass passage, and in the draft mode thesecond open and close member is operated to open the bypass passage sothat a volume of air introduced to the first outlet port increases. 14.The air conditioning unit according to claim 13, wherein the second openand close member is disposed at a position upstream of the bypasspassage.
 15. The air conditioning unit according to claim 13, whereinthe first heat exchanger defines an opening that opens to the bypasspassage.
 16. An air conditioning unit for a seat for blowing air from aseat surface, comprising: a duct defining an inlet port and a passagespace through which air introduced in the inlet port flows, the passagespace separating into a first passage and a second passage, the firstpassage defining a first outlet port through which air is blown to theseat surface, the second passage defining a second outlet port throughwhich air is discharged, the duct further defining a bypass passage thatdiverges from the passage space and communicates with the first outletport of the first passage; a heat exchanger unit disposed between theinlet port and the first and second outlet ports in the duct, the heatexchanger unit having a thermoelectric effect element, a first heatexchanger, and a second heat exchanger, the thermoelectric effectelement having a first side and a second side, one of the first side andthe second side radiating heat and the other one of the first side andthe second side absorbing heat according to a flow direction of anelectric current in the thermoelectric effect element, the first heatexchanger disposed adjacent to the first side for performing heatexchange with air passing through the first passage, the second heatexchanger disposed adjacent to the second side for performing heatexchange with air passing through the second passage; and an air volumecontrol device disposed in the duct for changing a volume of air flowingin the bypass passage between a normal mode and a draft mode, wherein inthe normal mode the thermoelectric effect element is energized and airpassing through the first heat exchanger is introduced to the firstoutlet port and air passing through the second heat exchanger isdischarged from the second outlet port, and in the draft mode a ratio ofair introduced to the first outlet port to the air introduced in theinlet port is larger than that in the normal mode, wherein in the draftmode the air volume control device is operated so that a volume of airflowing through the bypass passage toward the first outlet port islarger than that in the normal mode.
 17. The air conditioning unitaccording to claim 16, further comprising: a blower unit disposed at aposition upstream of the inlet port of the duct for producing a flow ofair into the inlet port.
 18. The air conditioning unit according toclaim 16, wherein the bypass passage is located between the seat and thefirst heat exchanger, in the first passage.
 19. The air conditioningunit according to claim 16, wherein in the draft mode an electriccurrent supply to the thermoelectric effect element is controlled suchthat a heat exchange rate of the first and second heat exchangers issmaller than that in the normal mode.
 20. The air conditioning unitaccording to claim 16, further comprising: a first open and close memberdisposed upstream of the second heat exchanger, wherein the first openand close member is operated to open and close the second passage forcontrolling a volume of air introduced to the second outlet port, and inthe draft mode the first open and close member is operated to fullyclose the second passage.
 21. The air conditioning unit according toclaim 16, further comprising: a first open and close member disposeddownstream of the second heat exchanger to open and close the secondpassage, wherein when the first open and close member fully closes thesecond passage the air passing through the second heat exchanger isallowed to flow in the first passage and is restricted from flowing tothe second outlet port, when the first open and close member opens thesecond passage the air passing through the second heat exchanger isrestricted from flowing in the first passage, and in the draft mode thefirst open and close member is disposed to fully close the secondpassage.
 22. The air conditioning unit according to claim 21, whereinthe first open and close member is formed of a material that deformsaccording to an ambient temperature, and the second passage is open andclosed according to deformation of the first open and close member. 23.The air conditioning unit according to claim 16, wherein the air volumecontrol device includes a second open and close member disposed to openand close the bypass passage, and in the draft mode, the second open andclose member is operated to open the bypass passage so that a volume ofair introduced to the first outlet port increases.
 24. The airconditioning unit according to claim 23, wherein the second open andclose member is disposed upstream of the bypass passage.
 25. The airconditioning unit according to claim 16, wherein the first heatexchanger forms an opening that opens to the bypass passage.